In large stationary boiler tube installations, "hot spots" often develop in the tube and instead of replacing the entire tube it has been found desirable to cut out the defective section of the tube and insert in its place a new section of tube. In order to weld the new section to the old section both must be chamfered to facilitate the welding operation. Existing tube chamfering machines are generally of bulky and heavy construction and cannot conveniently be used in close quarters in the boiler. The invention is also applicable in many other industries such as in shipbuilding, nuclear plants, etc.